Blue stones

An interesting Breton word I came across today is mein-glas, or slates (literally, ‘blue stones’). The French equivalent is ardoises, which I had to look up as it’s not a word that crops up every day, unless you’re a roofer or builder.

The Breton word is made up of mein (stones – singular maen) and glas (blue/green), and the French word is of uncertain, possibly Gaulish origin – the ard part might come from the Gaulish word *ard(u) (high), as in the Ardennes [source]. The ard element is also found in the Gaelic languages meaning high, tall, elevated.

The Welsh traditional song ‘Ar Lan y Mor’ (‘On the Seashore’, or thereabouts) features ‘cerrig gleision’ – blue rocks (using an old plural form of ‘glas’). I’ve never been given a satisfactory explanation of what is meant by this, but perhaps it is referring to slate – or some other stone of bluish hue?

Colour terms are, in Welsh, quite versatile, ‘glas’ being used to mean ‘blue’, ‘grey’ and ‘green’ (perhaps the rocks in the song are covered with algae), and ‘coch’ for a spectrum of colours from poppy red to dead bracken.

In Welsh ‘maen glas’ which has also the same literal meaning as Breton ‘maen-glas’ ie. ‘blue stone’ is Welsh for turquoise (the stone) which is ‘maen-turkez’ in Breton.
Welsh also has for ‘turquoise’: glasfaen; glaswyrdd & gwyrddlas.

As David has commented above and has been a blog topic on Omniglot in the past, Welsh colours terms are quite versatile; your ‘cerrig gleision’ could also be ‘silver stones’ alluding to ‘arian gleision’ = silver coins, coins the colour of silver. In North Wales ‘glas’ is also an intensifier in certain expressions and denotes extremity : eg extreme lateness, uncontrolled anger, best effort etc.

The ‘ard’ element also found in the Gaelic meaning high, tall, elevated used to be present in Welsh but the word is obsolete now: *ardd, (hill; high) but it is still current in Cornish: ardh n.m height; high place.

Would ‘ard’ be connected with the English word ‘arduous’ – “hard to accomplish, difficult to do,” from Latin arduus “high, steep,” also figuratively, “difficult,”?

Yenlit – ard might come from the same ultimate root as arduous and arduus: the Proto-Indo-European root *eredh- (to grow, high), which is also the root of ortho- [source]. I don’t know if the Celtic languages got it directly from PIE or via Latin or Greek (from ὀρθός [orthos] – straight, true, correct, regular)

I had connected Gaelic ‘ard’ with Welsh ‘allt’ (=hill, hillside) and hence with Latin ‘altus’ (=high). There again, the Welsh word also exists as ‘gallt’, which suggests that ‘allt’ was originally only a mutated form (…or perhaps it happened the other way round). A connection with Latin ‘arduus’ would be much more convenient.